There are few things more evocative in a tabletop RPG session than a hand-written letter with an impressed wax seal. The only problem is that traditional melted wax can be tricky, not to mention messy, to work with.* As an alternative, artist Katrina Crouch has an incredibly detailed tutorial on how to create them with a glue gun. It's aimed at brides doing their own wedding invitations, but the techniques are equally applicable to prop use.
*Personally, I also have some concerns about the safety of sealing wax. Most of the commercially available products are manufactured in China and carry a non-zero risk of being contaminated with lead and other heavy metals. I religiously use a respirator, but that just adds to the hassle factor of prepping a prop document.
